28"×32" Square Frame, Round Opening — Ductile Iron
Precast-friendly square frame with round access lid
Square outer frame (28"×32") with a round access cover — the configuration most U.S. precast concrete manhole top sections are formed for. Ductile iron casting, D400 traffic rated, custom lid markings on request.
| Product Code | LZB-DI-SQR-28x32-D400 |
|---|---|
| Clear Opening | 24" round opening (610 mm) within 28"×32" square frame |
| Overall Size | 28"×32" OD frame (710×810 mm) |
| Cover Thickness | ~1.5" (38 mm) |
| Frame Height | ~6"–8" (150–200 mm) |
| Material | Ductile Iron QT500-7 |
| U.S. Material Equivalent | ASTM A536 Grade 65-45-12 |
| Load Rating | D400 / AASHTO H-20 |
| Assembly Weight | 280–355 lb (127–161 kg) assembly |
| Surface Finish | Black bituminous coating |
| Marking | SEWER / STORM / city or utility ID, customizable |
| Locking | Bolt-down with two locking points (optional) |
- · ASTM A536 Grade 65-45-12
- · AASHTO H-20 / D400
- · AASHTO M306
Configuration matches many SPPWC and East Coast precast top-slab cutouts; project drawings reviewed for exact fit.
Why specify this
- ✓ Square frame keys cleanly into rectangular precast top slabs
- ✓ Round cover preserves the standard 24" maintenance access opening
- ✓ D400 traffic-rated for in-street installation
- ✓ Anti-settlement frame profile, non-rocking seat
- ✓ Available with watertight gasket configuration
Many precast concrete manhole top slabs are formed with a rectangular cutout rather than a round one — it simplifies the formwork and gives the structural concrete cleaner load paths. Pairing that rectangular cutout with a square frame and round cover gives you the best of both: clean precast geometry plus a standard 24” round access opening for normal maintenance work.
This product is sized for the most common precast top-slab cutout dimensions. For non-standard cutouts, send the precast drawing and we’ll confirm fit before quoting.
More from Ductile Iron Covers
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Utility vault and valve box square access
Need LZB-DI-SQR-28x32-D400? Get a quote in 48 hours.
Share your project details — quantity, delivery terms, and any drawing or SPPWC plan reference. We confirm fit and pricing, direct from the factory.